Electromagnets for use in connection with a playfield of an amusement game device, such as a pinball machine, a redemption game, etc., of the commercial type, e.g., revenue generating, and the non-commercial type, e.g., home entertainment, are known in the art. By way of example, U.S. Pat. No. 4,373,725 and U.S. Pat. No. 5,673,913 (incorporated herein by reference in their entirety) illustrate and describe a pinball game in which an electromagnet is positioned on or below the playfield. A computer-controlled circuit is coupled to the electromagnet and, under control of the computer-controlled circuit, the electromagnet is operable to control a ball moving upon the playfield, e.g., to alter trajectories of the ball, to capture and hold the ball, and/or to impart random motion to the ball.
When an electromagnet is to be positioned on the playfield, an iron alloy magnet core that protrudes thru the surface of the wood playfield board is typically utilized. As will be appreciated, the exposed magnet core provides the most powerful application of the device because the energized magnet core can come in direct contact with the steel pinball. In such an application, it is also important that the magnet core be installed flush to the surface of the playfield board to prevent the ball from skipping when it encounters the edge of the magnet core and that the diameter of the magnet core be optimized around the dimensional parameters of the steel pinball as a magnet core that is either too small or too large adversely affects the magnetic flux density making it difficult to grab the moving pinball as it passes at speed over the magnetic core, to hold the pinball on the magnetic core, and/or to move or oscillate the pinball via use of the magnet core under software control.
Given the effective diameter of the core, as the pinball is caught by the energized magnet core, the ball oscillates across the surface of the magnet core. During this motion it is common for the ball to cross back and forth across the perimeter edge of the magnet core and the associated edge of the hole in the wood playfield board. This motion undesirably tends to erode and wear the edge of the wood at the edge of the playfield board thru which the magnet core protrudes.